At Home - Bill Bryson [116]
Eiffel’s Tower under construction, Paris, 1888 (photo credit 10.1)
In its finished state, the Eiffel Tower seems so singular and whole, so couldn’t-be-otherwise, that we have to remind ourselves that it is an immensely complex assemblage, a fretwork of eighteen thousand intricately fitted parts, which come together only because of an immense amount of the very cleverest thought. Consider just the first 180 feet of the structure, up to the first platform—already the height of a ten- or twelve-story building. Up to that height the legs lean steeply inward at an angle of 54 degrees. They would clearly fall over if they weren’t braced by the platform. The platform just as clearly couldn’t be up there without the four legs underneath to support it. The parts work flawlessly when brought together, but until they are brought together they cannot work at all. Eiffel’s first challenge, therefore, was to devise some way to brace four immensely tall and heavy legs, each straining to topple inward; then, at the right moment, be able to ease them into position so that all four came together at exactly the right points to support a large and very heavy platform. An incorrect alignment of as little as one-tenth of one degree would have put any leg out by a foot and a half—far more than could be corrected without taking everything down and starting all over again. Eiffel effected the delicate operation by anchoring each leg in a giant container of sand, like a foot in a large boot, which held them securely during construction. Then, when work on them was complete, the legs could be eased into position by letting sand out of the boxes in a carefully controlled manner. The system worked perfectly.
But that was only the start of things. Above the first platform came another eight hundred feet of iron framework made from fifteen thousand mostly large, unwieldy pieces, all of which had to be swung into place at increasingly challenging heights. Tolerances in some places were as little as one-tenth of a millimeter. Some observers were convinced that the tower couldn’t support its own weight. A professor of mathematics filled reams of paper with calculations and concluded that when the tower was two-thirds up, the legs would splay and the whole would collapse in a thunderous fury, crushing the neighborhood below. In fact, the Eiffel Tower is pretty light at just 9,500 tons—it is mostly air, after all—and needed foundations just seven feet deep to support its weight.
More time was spent designing the Eiffel Tower than building it. Erection took under two years and came in well under budget. Just 130 workers were needed on-site, and none died in its construction—a magnificent achievement for a project this large in that age. Until the erection of the Chrysler Building in New York in 1930, it would be the tallest structure in the world. Although by 1889 steel was displacing iron everywhere, Eiffel rejected it because he had always worked in iron and didn’t feel comfortable with steel. So there is a certain irony in the thought that the greatest edifice ever built of iron was also the last.
The Eiffel Tower was the most striking and imaginative large structure in the world in the nineteenth century, and perhaps the greatest structural achievement, too, but it wasn’t the most expensive building of its century or even of its